To crawl into bed with someone while they are sleeping and put your arm around them, then get up and walk out of the room as the person wakes up.

Originated from the "Georgetown Cuddler" incidents at Georgetown University, where an unknown suspect would go into the unlocked dorm rooms or apartments of young university females, and get into bed with them.

I woke up in the middle of the night to find a stranger in my bed giving me a Georgetown cuddle.